Here's why:
* Champak is a generic term used in various languages to refer to different fragrant flowering plants.
* Frangipani specifically refers to the genus *Plumeria*, a popular ornamental tree native to Mexico, Central America, and the Caribbean.
* Bengali champak is a specific variety of *Plumeria* called Plumeria alba, known for its white, fragrant flowers.
Therefore, the most accurate translation of "Bengali champak" into English is frangipani, specifically white frangipani or Plumeria alba.